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TeV-Gamma Ray Astrophysics with the H.E.S.S. Telescopes

TeV-Gamma Ray Astrophysics with the H.E.S.S. Telescopes. Thomas Lohse Humboldt University Berlin. NordForsk Network Meeting in Astroparticle Physics Bergen, November 10, 2006. Veritas. MAGIC. in construction. H.E.S.S. CANGAROO III. Cherenkov Telescopes (3 rd Generation).

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TeV-Gamma Ray Astrophysics with the H.E.S.S. Telescopes

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  1. TeV-Gamma Ray Astrophysics with the H.E.S.S. Telescopes Thomas Lohse Humboldt University Berlin NordForsk Network Meeting in Astroparticle Physics Bergen, November 10, 2006

  2. Veritas MAGIC in construction H.E.S.S. CANGAROO III Cherenkov Telescopes (3rd Generation)

  3. TeV -Astronomy: The Physics Shopping List • Cosmic ray origin and acceleration • Supernova remnants • Starburst galaxies • Clusters of galaxies • Unidentified galactic sources/surveys • Astrophysics of compact objects • AGNs • Micro-Quasars & Stellar-mass black holes • Pulsars • Gamma ray bursts • Cosmology • Diffuse extragalactic radiation fields via cutoff in AGN spectra • Astroparticle physics • Neutralino annihilation in DM halos

  4. H.E.S.S. High Energy Stereoscopic System MPI für Kernphysik, Heidelberg Humboldt-Universität zu Berlin Ruhr-Universität Bochum Universität Erlangen-Nürnberg Universität Hamburg Landessternwarte Heidelberg Universität Tübingen Ecole Polytechnique, Palaiseau APC, Paris Universite Paris VI-VII CEA Saclay CESR Toulouse GAM Montpellier LAOG Grenoble Paris Observatory LAPP Annecy Durham University Dublin Inst. for Advanced Studies NCAC Warsaw Astronomical Observatory Cracow Charles University Prag Yerewan Physics Institute North-West University, Potchefstroom University of Namibia, Windhoek

  5. Farm Göllschau, Khomas Hochland, 100 km from Windhoek 23o16’ S, 16o30’ E, 1800 m asl H.E.S.S. Site • Clear sky • Galactic centre culminates in zenith • Mild climate • Easy access • Good local support (UNAM etc.)

  6. H.E.S.S. Phase I 4 telescopes operational since December 2003 Energy threshold (for spectroscopy): 100 GeV Single shower resolution: 0.1 Pointing accuracy: ≲ 20 Energy resolution:  20% June 2002 September 2003 February 2003 December 2003

  7. 960 pixel PMT camera Pixel size: 0.16° On-board electronics Weight: 900 kg 13m dish, mirror area 107 m2 382 spherical mirrors, f =15m Point spread 0.03°-0.06°

  8. Selected Results from H.E.S.S. • Particle Acceleration in Supernovae • The Galactic Centre • The Gamma Ray Horizon • Gamma Rays from a Super-Massive Black Hole • Gamma Rays from a Micro-Quasar

  9. Supernovae

  10. But what about hadrons (protons and nuclei)? Pulsar Wind Nebula: Electron wind from centralpulsar heats the cloud Synchrotron radiation The Standard Candle for TeV -Astronomy Crab Supernova 1054 a.D. d = 2 kpc optical 1 lightyear

  11. Cassiopaeia A Supernova 1658 a.D. d = 2,8 kpc X ray picture • “Shell Type” SNR: • no electron wind from pulsar • gamma signal from shell regions not totally drowned in that of electron wind • good source class to observe hadron acceleration

  12. RX J1713.73946 RX J1713.73946 E 210 GeV H.E.S.S. 2004 E  210 GeV H.E.S.S. 2004 resolution resolution First Resolved Supernova Shells in -Rays RX J0852.04622 H.E.S.S. 2005 E 500 GeV Strong correlation with X-ray intensities • SN-Shells are accelerating particles up to at least 200TeV! • But are these particles protons/nuclei or electrons?

  13. Matter Density B Ee Stars Dust Cosmic Proton Accelerators Cosmic Electron Accelerators CMB B Ee Inverse Compton Synchrotron Radiation 0 Synchrotron Radiation of Secondary Electrons Electron or Hadron Accelerator? radio infrared visible light X-rays VHE -rays E2 dN/dE log(E)

  14. B7,9,11G 2.0,2.25,2.5 EGRET 2.0 B10G Electron accelerator fits for RX J1713.73946: • Continuous electron injection over 1000 years • Injection spectrum: power law with cutoff H.E.S.S. • large  & injection rate  bremsstrahlung important • needs tuning at low E • IC peak not well described • B-field low for SNR shell

  15. RX J1713.73946 H.E.S.S. Proton accelerator fit: • Continuous proton injection over 1000 years • Injection spectrum: power law, index 2 • Different cutoff shapes & diffusion parameters

  16. Galactic Centre HESS J1745290 HESS J1632478 HESS J1825137 RX J1713.73946 HESS J1616508 HESS J1837069 HESS J1804216 HESS J1745290 HESS J1708410 HESS J1834087 HESS J1813178 HESS J1614518 G0.90.1 HESS J1747281 HESS J1713381 HESS J1634472 HESS J1640465 HESS J1702420 Galactic Centre

  17. Possible Interpretation: Dark Matter annihilation? Crab GC MAGIC H.E.S.S. • no visible cut-off  rather large mass • measured flux  large cross-section and/or DM density 20 TeV Neutralino 20 TeV Kaluza Klein particle … unlikely !

  18. Galactic Centre Neighbourhood SNR G0.90.1 HESS J1747281 Galactic Centre HESS J1745290 EGRET GeV--sources ~150 pc

  19. HESS J1745290 Galactic Centre Neighbourhood ...point sources subtracted • first resolved detection of diffuse TeV--radiation • cosmic rays (hadrons) interacting with molecular clouds molecular clouds density profiles ~150 pc

  20. diffuse radiation expected flux for CR spectrum observed on earth Cosmic Ray Spectrum at the GC... is very different from the one at earth Cosmic rays are much harder and have 3 larger density around the GC Possible reason: Close-by source population Possibly single SN-explosion

  21. The Gamma Ray Horizon

  22. Blazars • General Active Galactic Nuclei (AGN): • Supermassive black holes, M  109 M • accretion disk and relativistic jets • Blazar-Typ: Jet points towards the earth • Doppler-boost  TeV -radiation

  23.  e+ e-  dN/dE dN/dE E E Absorption in (infrared) extragalactic background light (EBL) (TeV) + (EBL)  e+e- Measurement of EBL ( Cosmology) Physics of compact objects, acceleration/absorption in jets,…

  24. Cut-off Energy and -Ray Horizon PG 1553113

  25. EBL Hardest plausible source spectrum  = 1.5 EBL Unfolding of Measured Spectra Too much EBL 1 ES 1101  = 2.9±0.2 H 2356 (x0.1)  = 3.1±0.2 H 2356 (x 0.1) G = 3.1±0.2 Preliminary

  26. excluded by H.E.S.S. Assumed shape for rescaling H.E.S.S. upper bound fromspectral shapes of 1ES 1101-232 (z = 0.186) H 2356-309 (z = 0.165) New Upper Bound on EBL Density EBL density seems 2 smaller than expected! Little room for EBL sources other than galaxies (early stars…) Direct IRTS Measurements Upper Limits Lower Limits (Galaxy Counts)

  27. M87 Gamma Rays from the Rim of a Super-Massive Black Hole

  28. Radio VHE -Rays 99.9% c.l. extension upper limit host galaxy (optical) • Radio Galaxy, Virgo Cluster, d16Mpc • Central 3109M⊙ Black Hole, RS1015cm • Relativistic Plasma Jet at 30  Blazar M87 Is there a better way to constrain the source size?

  29. relativisticDoppler factor v  c reasonable: 150  time smearing: R/c source variability: t* ≳ R/c shortest observable variability: t ≳R/c  upper limit on source size: R≲ct Yes, there sometimes is: Source variability! R source 

  30. Doubling times of 2 days observed during 2005 high state of M87 Radio optical X-ray knots (jet) nucleus • Knots in jet are excluded as sources • High energy particles created close to black hole horizon

  31. Gamma Rays from a Micro-Quasar

  32. superior conjunction 0.058 Periastron 0 Apastron 0.5 inferior conjunction 0.716 observer LS 5039 • Massive star M20M⊙ • compact object: 1.5-5M⊙ neutron star or black hole? • Orbital Period 3.9 days • Eccentric orbitbinary separation 2-4.5R*

  33. superior conjunction 0.058 Periastron 0 Apastron 0.5 inferior conjunction 0.716 observer Paredes et al. 2000 LS 5039 • Faint X-ray emissionslightly variable • Extended pc-scale radio emission possibly from jets (v0,2 c)

  34. 0.058 0 0.5 0.716 observer VHE -Ray Lightcurve folded with orbital period H.E.S.S. Modulation  absorption in radiation field  central emission (1au)

  35. VHE Spectral Modulation • modulation strength strongly energy dependent • not explainable by pure absorption effects • complicated interplay between production & absorption mechanisms The central engine starts to reveal its physics

  36. The Future: H.E.S.S. Phase II • Large telescope under construction • Improve sensitivity: 4 small  1 largebetter than8 small • Reduce threshold to O(20 GeV)

  37. Summary • Very successful initial years of H.E.S.S. Phase I • Many new sources & several fundamental discoveries • The VHE -ray sky is well populated and complex • Expect “bright” future

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